Jobs often was seen as a difficult and demanding person, expecting perfection from the people around him and highly critical of those who failed to meet those expectations. He was also sometimes portrayed as petty and selfish in his dealings with other people. But of course, there was more than one side to the man. "Becoming Steve Jobs" appears to be an effort to shed light on some of the more positive aspects to Jobs. Schlender, who covered Jobs for almost 25 years, told the Times that he wanted to write the book because he felt there was a side to the man's personality that had yet to be conveyed.

Last week, Eddy Cue, Apple's head chief of software and Internet services, tweeted: "Best portrayal is about to be released -- Becoming Steve Jobs (book). Well done and first to get it right."

As one example of Jobs' more humane side, an excerpt of "Becoming Steve Jobs" published in tech magazine Fast Company tells how now-CEO Tim Cook offered part of his liver to Jobs when the latter needed a liver transplant and Cook discovered that they shared the same rare blood type.

"I really wanted him to do it," Cook said in the book. "He cut me off at the legs, almost before the words were out of my mouth. 'No,' he said. 'I'll never let you do that. I'll never do that!'"

"Somebody that's selfish," Cook said, "doesn't reply like that.

Meanwhile, Apple execs are slamming a previous biography of Jobs, an authorized edition titled simply "Steve Jobs" by Walter Isaacson that was published in 2011.

In the excerpt of "Becoming Steve Jobs," Cook lashes out at the Isaacson bio.

"I thought the [Walter] Isaacson book did him a tremendous disservice," Cook said. "It was just a rehash of a bunch of stuff that had already been written, and focused on small parts of his personality. You get the feeling that [Steve's] a greedy, selfish egomaniac. It didn't capture the person. The person I read about there is somebody I would never have wanted to work with over all this time."

"Ive said that he'd read only parts of the book, but had seen enough to dislike it, for what he called inaccuracies," The New Yorker wrote. "'My regard couldn't be any lower,' he said, with unusual heat."

Speaking with the Times, Isaacson defended his book, saying that he attempted a balanced view of Jobs that "did not sugarcoat the Apple co-founder's flaws." To write his bio, Isaacson spoke with Jobs more than 40 times and with more than 100 of his friends, relatives and colleagues, such as Cook, Ive and Cue, the Times noted.

"My book is very favorable and honest, with no anonymous slings," Isaacson said.

"Becoming Steve Jobs" is actually an unauthorized biography, culled from interviews with four Apple executives, including Cook. At first, the book's authors, Schlender and Tetzeli, were given the cold shoulder in seeking out interviews with Apple brass, the Times reported. But Schlender said he thinks the pair's patience and quiet perseverance" eventually won over Apple. The authors showed the final draft to Apple, but the company itself had no "editorial input whatsoever," Tetzeli added.

"After a long period of reflection following Steve's death, we felt a sense of responsibility to say more about the Steve we knew," Apple spokesman Steve Dowling told the Times. "We decided to participate in Brent and Rick's book because of Brent's long relationship with Steve, which gave him a unique perspective on Steve's life. The book captures Steve better than anything else we've seen, and we are happy we decided to participate."